This invention relates to an illuminated switch assembly of the type having a display panel with a first area of graphic indicia illuminated to display the function of the switch and a second area illuminated to provide an indication that the function is activated.
Pushbutton switches, such as the type found in automobiles, are sometimes required to be backlit. This is for low light viewing of the graphic indicia on the face of the pushbutton which illustrates the function associated with the switch. In some instances, it may also be required to indicate that the function has been activated by means of an indicator light on this same surface. For aesthetic reasons, it is undesirable to have the "on" indicator interferingly backlit by the light source for the graphics, or vice versa. This is especially true when the two light sources are different in color. It is therefore a primary object of the present invention to provide a cost effective means of stopping the transmission of light between different adjacent backlit areas on the same surface.
In the particular application with which the present invention is concerned, the light source for back-lighting the graphics area is an electroluminescent panel and the "on" indicator light source is either a miniature incandescent lamp or a light emitting diode. In this application, one possible solution to the light leakage problem is to position the indicator light source within an opaque shroud which is part of the button. With such an arrangement, the indicator light source could either move with the button or be stationary, having the button and shroud move relative to it. However, both of these alternatives present problems. Thus, if the indicator light source moves with the button, then the connection to a power source for the light source becomes difficult, since it may require additional parts, resulting in a higher cost. If, on the other hand, the light source does not move with the button, it must be mounted relatively close to the button. In many applications, this may not be possible due to size constraints placed upon the button and the graphics. In turn, this limits the wall thickness of the shroud in the button because the extension of the walls is dependent upon the thickness of the walls at the parting line of the plastic button mold, since the walls must be tapered to allow easy ejection from the mold. This limits how far the walls of the shroud can extend down around the indicator light source. In the particular application for which the present invention was developed, the light source is mounted so far from the button that the shroud walls cannot be made long enough to envelope the light source or sufficiently baffle the light. Another possible solution is to place a separate shroud around the indicator light source. However, this is disadvantageous since it would require an additional part, resulting in a higher cost. It is therefore another object of the present invention to overcome the aforementioned problems.